Norwegian police has blocked a large area in central Oslo and detained one suspect on Saturday night after finding a bomb-like object, police said in a tweet.

The man who has the status of a suspect has been arrested and taken in for questioning after the subject was found in Gronland in Oslo, police told public broadcaster NRK.

"There was a police patrol who came across a man they became interested in. In connection with him, they found a box with content that police believe is suspicious," Svein Arild Jorundland, a police commander at the site, was quoted as saying.

"I can not answer (if is a bomb), but it is an object that is about 30 times 30 centimeters -- that is to say there is big potential for damage, but it is of such a nature that we want the bomb group to examine it," Jorundland told NRK.